The authors used an exclosure study to see if birds and lizards had an impact on the abundance of insects in a shade coffee plantation, in particular two that damage coffee (the coffee leafminer and flatid planthopper). When birds or birds and lizards were excluded, the abundance of larger insects increased. In particular, planthoppers increased greatly when birds were unable to prey upon them. The leafminers, which are serious pests of coffee and are small insects, increased if lizards were not able to prey on them.

This study indicates that birds and lizards (which the senior author found more abundant in shade coffee than sun coffee in Puerto Rico, presented in her Masters’s thesis) may help control the numbers of some coffee pests in shade plantations. Another important finding is that neither birds nor lizards interfered with the numbers of other natural insect enemies of coffee pests, parasitoid wasps.